Confined space and cations enhance the power of a chiral auxiliary: photochemistry of 1,2-diphenylcyclopropane derivativesElectronic supplementary information (ESI) available: experimental details of irradiation, extraction and analysis of products, and representative synthesis and spectral data of reactant cis and product trans isomers; total number of pages 21. See http://www.rsc.org/suppdata/cc/b2/b200640e/
Confined space and cations enhance the power of a chiral auxiliary: photochemistry of 1,2-diphenylcyclopropane derivativesElectronic supplementary information (ESI) available: experimental details of irradiation, extraction and analysis of products, and representative synthesis and spectral data of reactant cis and product trans isomers; total number of pages 21. See http://www.rsc.org/suppdata/cc/b2/b200640e/
Reactive-State Spin-Dependent Diastereoselective Photoisomerization of <i>trans,trans</i>-2,3-Diphenylcyclopropane-1- carboxylic Acid Derivatives Included in Zeolites
作者:J. Sivaguru、Tetsuya Shichi、V. Ramamurthy
DOI:10.1021/ol026695l
日期:2002.11.1
[reaction: see text] The asymmetric induction facilitated by a chiral auxiliary during the photoisomerization of trans,trans-2,3-diphenylcyclopropane derivatives depends on the medium (solution vs zeolite) and the reactive state (singletvs triplet). Within zeolites, direct excitation most likely proceeds via a zwitterionicintermediate, while triplet sensitization most likely proceeds via a diradical
Zeolites significantly enhance the influence of chiral auxiliaries during photochemical reactions. The generality of this phenomenon has been tested with three independent examples. Chiral auxiliaries that lead to 1:1 mixtures of diastereomers in solution give products in up to 80% diastereomeric excess in the presence of faujasite type zeolites. (C) 2000 Elsevier Science Ltd. All rights reserved.